Senate ratification of the new Strategic Arms Reduction Treaty appears headed for a close vote this week, as Democrats furiously lobbied wavering Republicans on Monday to join them in cobbling together the necessary votes.

Sen. Scott Brown (R-Mass.) announced to reporters late Monday afternoon that he would support ratification, giving START one of the nine GOP votes needed to finalize the nuclear weapons treaty with Russia. Ratification requires a supermajority of two-thirds of all Senators present and voting, 67 votes in the full chamber, and the Democratic Conference is united behind it.

The Democrats are looking for the remaining votes from two tiers of GOP Senators, with the first group of five viewed as a lock. The six Republicans in the second group are believed to be undecided, and their votes are likely to determine whether START is ratified before the conclusion of the 111th Congress.

&ldquo;I think it will be a very close call,&rdquo; Senate Foreign Relations ranking member Dick Lugar (R-Ind.), who staunchly supports ratification, said Monday.

Brown&rsquo;s and Lugar&rsquo;s votes are included in the first tier, as are those of GOP Sens. Susan Collins (Maine), Olympia Snowe (Maine) and Bob Corker (Tenn.). Collins and Snowe continue to hedge, but Corker signaled during a brief interview that he will be on board.&nbsp;&ldquo;I&rsquo;m still looking to complete getting the i&rsquo;s dotted and t&rsquo;s crossed. I think that&rsquo;s going to occur,&rdquo; the Tennessee Republican said. &ldquo;The administration has been very constructive in dealing with issues as we&rsquo;ve moved along.&rdquo;

Brown&rsquo;s and Corker&rsquo;s comments delivered a boost to President Barack Obama and other START supporters who want the treaty ratified before Christmas, only days away.

Minutes after Brown&rsquo;s announcement, Senate Foreign Relations Chairman John Kerry declared during a news conference that he expects the treaty to achieve ratification. The Massachusetts Democrat would not speculate on how close the vote might be, but he expressed confidence that it would be successful.

&ldquo;I anticipate we&rsquo;re going to ratify this treaty. I&rsquo;ll give you the vote count after it&rsquo;s taken place,&rdquo; Kerry said, with Armed Services Chairman Carl Levin (D-Mich.) and Select Intelligence Chairman Dianne Feinstein (D-Calif.) at his side. The three spoke after the Senate emerged from a closed session held to debate classified aspects of START.

A vote to end debate and proceed to a final ratification vote is scheduled for Tuesday. That motion requires 60 votes. If successful, a vote on ratification would likely occur Thursday, unless Republicans agreed to hold the vote sooner.

The second tier of possible Republican supporters comprises Conference Chairman Lamar Alexander (Tenn.) and Sens. Bob Bennett (Utah), Judd Gregg (N.H.), Johnny Isakson (Ga.), Mark Kirk (Ill.) and George Voinovich (Ohio). Of that group, Bennett, who is retiring, appears to be the most likely to vote for ratification at this point, despite his close relationship with Minority Leader Mitch McConnell (R-Ky.), who is opposed.

Armed Services ranking member John McCain (R-Ariz.) and his ally on national security matters, Sen. Lindsey Graham (R-S.C.), appear to be leaning toward opposing ratification despite heavy courting by the White House. McCain offered an amendment to START last week, but it was defeated. Graham said Monday that he continues to have substantive disagreements with START, and he is upset that Democrats have pushed for ratification during the lame-duck session.

Republican Senate aides monitoring the GOP whip count on START say Isakson is inclined to support ratification but could be influenced by Sen. Saxby Chambliss (R-Ga.), who appears to be headed toward voting &ldquo;no.&rdquo; Voinovich, who is retiring, previously voiced concerns about the treaty but has been the subject of intense lobbying by the administration.

Gregg has already announced his support for START on its merits, but he has made clear he might oppose ratification as a courtesy to Republicans who contend there has been insufficient opportunity to debate and amend the treaty. Alexander also has signaled his support but could vote &ldquo;no&rdquo; out of solidarity with GOP leadership. He is close with McConnell and Minority Whip Jon Kyl (Ariz.), who is leading the Republican opposition to START.

Kyl told reporters following the closed session that he would vote against ratification if the vote is held this week. Like several of his GOP colleagues, Kyl continues to express concerns that START could hamper U.S. missile defense capabilities, and he complains that the Obama administration has not taken adequate steps to fund a modernization of the nation&rsquo;s existing nuclear stockpiles.

Additionally, the Minority Whip has repeatedly argued that START has not received sufficient debate, given that the treaty has been considered simultaneously with other legislation since it hit the floor Thursday. Meanwhile, supporting START carries political implications for Republicans, as many conservative activist groups and commentators are strongly urging the Senate minority to push consideration of the treaty to next year, when the GOP&rsquo;s ranks will grow from 42 to 47 Members.

&ldquo;It&rsquo;s further complicated by more things to do and even less time to do it here before Christmas,&rdquo; Kyl said, referring to unfinished business such as a continuing resolution to fund the government and a bill to fund the health care costs of Sept. 11 first responders.

Obama signed START with Russian President Dmitry Medvedev this year and has made ratification of the document by year&rsquo;s end his No. 1 foreign policy priority. As part of the administration&rsquo;s lobbying effort, Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, sent Kerry a letter Monday urging that the treaty be immediately ratified.

Democrats dismissed Republican objections to START and contended that immediate ratification is vital to national security. They beat back three GOP amendments Monday evening: Amendments by Sens. James Inhofe (Okla.) and John Thune (S.D.) were both rejected by votes of 33-64, while a third by Sen. George LeMieux (Fla.) fell by a vote of 35-62. All previous GOP amendments have also been defeated, with Democrats arguing that the acceptance of any proposal would kill START.

&ldquo;I believe very strongly that from an intelligence perspective, we are much better off with the treaty than without the treaty,&rdquo; Feinstein said. &ldquo;Without the treaty we have nothing, and I think the Russians have indicated the treaty would not be renegotiated. Therefore we go blind and we go dark, and I think that is a problem.&rdquo;